Electronic musical instrument



Nov. 23, 1965 SHIGEAKI MAIBUCHI ETAL ELECTRONIC MUSICAL INSTRUMENT Filed Oct. 13. 1960 4 Sheets-Sheet 2 MM 6 T 1965 SHIGEAKE MABUCZHI ETAL 3,

ELECTRONIC MUS ICAL INSTRUMENT Filed Oct. 13, 1960 4 Sheets-Sheet 3 United States Patent 3,219,745 ELECTRONIC MUSKCAL INSTRUMENT higeaki Mabuchi and Kiyohiko itch, Haniainatsu-shi,

Japan, assignors to Nillon Galrki Seizo Kabushiiri Kaisha, Hamamatsu-shi, Japan Filed Get. 13, 1960, Ser. No. 62,390 Qlaims priority, application Japan, Oct. 24, 1959, 34/ 33,327 2 Claims. (Cl. 841.13)

This invention relates to electronic musical instruments, and more particularly it relates to a new electronic musical instrument having a form and operational control arrangement similar to those of an organ console.

It is an essential object of the invention to provide an electronic musical instrument of high stability, capable of creating amply satisfactory musical tones.

It is another object of the invention to provide an electronic musical instrument which, at the same time that it fully achieves the above-stated object, is low in cost, requires almost no adjustment during its manufacture, requires almost no maintenance care after manufacture, has a low rate of consumption of electric power, and is adaptable for assembly into a small, compact unit.

It is yet another object of the invention to provide an electronic musical instrument as stated above, which is free of the disadvantages accompanying conventional, electronic musical instruments, particularly electronic organs.

The distinctive features of the musical instrument of this invention may be summarized as follows:

(1) In the composition of the sound source component, the frequency of the signal from a master oscillator, which oscillates at the frequency of, or twice the frequency of, the highest octave, is divided into the necessary number of stages by frequency dividers which based on parametric excitation. These elements in combination constitute the sound source.

(2) In the master oscillator, twelve LC oscillators comprising semiconductors, capacitors, coils, and resistors are used, and these become the driving power sources for the initial stage of the immediately succeeding, parametric excited frequency divider. Since temperature compensation and other measures are taken in the circuit arrangement especially in order to attain frequency stabilization, there is almost no need for retuning once it has been tuned.

(3) Since parametric excited frequency dividers are used for dividing the frequencies into halves, their operation is stable. Moreover, the life of these dividers is practically permanent, requiring no replacements as in the case of electronic tubes. Furthermore, they require no adjustments during manufacture and do not suffer any effects due to temperature as in the case of transistors.

(4) Since so-called parametron-connections such as proposed by U.S. Patent No. 2,948,818 are used also in the circuits for effecting the rise and attenuation of the sounds, and their unique properties are fully utilized, the graphical curves of the said rise and attenuation are ideal, being curves of exponential functons. Furthermore, since the driving of the said circuits and gating of the sound signals are accomplished by the same contact, the contact mechanism for creating tone color and the keyboard contact mechanism for sound frequency selection need not be complex.

(5) In the case of the twelve notes of the lowest octave, the above-described circuits and the frequency dividers can be combined, whereby it is possible to economize on parts.

(6) The typical oscillation wave form is a sine curve, and a method wherein various harmonics are combined to compose various tone colors can be adopted in a simple manner, whereby it is possible to create a large number of tone colors having various distinctive features. If necessary, desired wave forms can be obtained by providing a wave forming circuit.

The details of the invention will be more clearly apparent by reference to the following detailed description of a few representative embodiments of the invention when taken in connection with the accompanying drawings in which the same or equivalent parts are designated by the same reference numerals or letters, and in which:

FIG. 1 is a schematic block diagram showing the prin cipal components composing a representative, electronic musical instrument according to the invention;

FIG. 2 is a schematic block diagram showing the com position of only one of twelve oscillator-divider systems in the electronic musical instrument of FIG. 1;

FIG. 3 is an electric circuit diagram showing one embodiment of the master oscillator of the electronic musical instrument of FIG. 1;

FIG. 4 is an electric circuit diagram for describing the method of exciting the initial stage of a frequency divider of the electronic musical instrument of FIG. 1;

FIG. 5 is an electric circuit diagram showing an embodiment of the frequency divider suitable for the electronic musical instrument of this invention;

FIG. 6 is a parametron circuit diagram for an explanation of the principle of the envelope circuit;

FIG. 7a and FIG. 7b are graphical representations indicating the oscillation wave form of a parametron, for an explanation of the principle of the envelope circuit;

FIG. 8 is an electric circuit diagram showing one embodiment of an envelope circuit according to the invention;

FIG. 9 is an electric circuit diagram showing the details of the composition of one system of twelve oscillator divider systems of an electronic musical instrument according to the invention.

Referring to FIG. 1, the block designated by the reference numeral 1 represents a sound source circuit, and that designated by the reference numeral 2 represents envelope circuits. (The circuits which effect tone rise and attenuation shall be hereinafter referred to by these terms.) The sound source circuit is divided into master oscillators and frequency dividers. However, one portion of the envelope circuits function doubly as frequency dividers. Sound source circuit 1 and envelope circuits 2 are connected as shown to a circuit 3 which creates tone colors by tone selection (strictly speaking, selection of tones of certain frequencies) and composition of various harmonics. Tone selection from the outside is accomplished by means of a keyboard mechanism 4, and the tone color circuit is controlled by means of a tone stop mechanism 5. The tone selection and tone color circuit 3 is composed almost entirely of contact mechanisms. Control of the envelope circuits, that is, control of the lengths of damping, is accomplished by means of contacts and control mechanism 6. The output obtained from the above mentioned circuits is amplified by an amplifier 7, and the resulting electrical output is converted into audible output by a loudspeaker 8.

The sound source circuit 1 of FIG. 1 contains 12 master oscillators, to each of which frequency dividers for dividing the respective frequency from said each master oscillator to the necessary extent are connected in cascade. Accordingly, there are 12 systems, each consisting of frequency dividers connected to a master oscillator. Each output from these oscillators and frequency dividers is passed through the tone selection and tone color circuit 3 and is led to the corresponding envelope circuit in the envelope circuits 2. This arrange ment as represented by one system is shown in detail in FIG. 2.

Referring to FIG. 2, let it be assumed that a master oscillator 9 produces an output at a frequency of 1, which is to be divided by frequency dividers 1t), 11, 12, 13, and 314. The frequency divider receives a signal of frequency 1 from the oscillator 9 and divides the same into one half to obtain a. signal of frequency f/ 2. Similarly, the frequency divider Ill produces a signal of frequency f/4. In the same manner frequencies of f/8, f/16, and f/ 32 are obtained from frequency dividers 12, 13, and 14, respectively.

The above-described master oscillator 9 and frequency dividers 10, Ill, 12, I3, and 14 are connected, through a tone selection and tone color circuit 3, to envelope circuits 15, 16, 17, i8, 19, and 20, respectively, so that signals of frequencies f, f/2, f/4, f/8, f/l6, and f/32 from the said oscillator and said frequency dividers enter the said envelope circuits I5, 16, 17, 13, 19, and Zti, respectively. The said circuit 3 is provided with a keyboard mechanism 4 and a tone stop mechanism 5 as was mentioned previously. The block designated by refer ence numeral 6 represents a unit comprising a group of contacts for controlling the envelopes and mechanism for actuating the said contacts. At the envelope circuits the frequencies of the input signals are halved; and, simultaneously, the desired rise and attenuation are given to the output signals issuing therefrom. The resulting envelope wave forms (principally the damping time) is controlled by the aforesaid envelope control contacts and contact actuating mechanism 6.

The envelope circuits 15, 16, 1'7, 18, 19, and are provided, respectively, with output terminals I, II, III, IV, V, and VI. Since the envelope circuit 15 accomplishes its function of receiving a signal of frequency 1 from the oscillator 9, halving the said frequency, and simultaneously transmitting the signal as a suitable, envelope wave form, a signal of frequency f/2 is obtained from the output terminal I. Similarly, signals of frequencies f/4, f/ 8, f/ 16, f/ 32, and f/ 64 are obtained from the output terminals II, III, IV, V, and VI, respectively.

The keyboard mechanism 4, the tone stop mechanism 5, and envelope control contacts and contact actuating mechanism 6 are all controllable as necessary from the outside when the musical instrument is being played.

The details of the master oscillators, the initial stages of the frequency dividers, and their excitation method will be best understood from a consideration of the following description.

The master oscillators consists of 12 oscillators which oscillate at frequencies corresponding to the oscillation frequencies of one octave of the musical instrument. It is more correct to consider these oscillators as being the power sources of excitation of the parametric excited frequency dividers which are connected thereafter to the said oscillators rather than oscillators of the tones of the highest octave as can be seen in an ordinary electronic organ.

FIG. 3 shows the circuit of one of the 12 oscillators in an embodiment wherein transistors are used. The transistor 21 has three electrodes, namely a collector electrode 22, a base electrode 23, and an emitter electrode 24. An inductor 25 and a capacitor 26 constitute factors which principally determine the oscillation frequency. A capacitor 27 and a variable resistor 28 are used for tuning. Resistors 29 and 30, together, are for stabilizing direct current; and resistor 31 and capacitor 32 are also for stabilizing the circuit. Resistors 33 and 34 are for imparting bias on the base electrode 23 of the transistor 21. An input terminal 35 through which is fed frequency modulated signals for the purpose of inducing a vibrato effect is connected, through a resistor 36 for coupling the modulated signals, to the base electrode 23 of the transistor 21, Direct-current power is supplied by a direct-current power source 37.

As schematically represented in FIG. 3, the above-described circuit is an ordinary LC oscillator, but among the elements determining the oscillation frequency in the actual embodiment of the invention, the capacitor 26 and the inductor 25 are so adapted that their temperature coefiicients have opposite signs, whereby correction is effected for variations due to temperature of the transistor 21. Fine adjustments of the frequency are made by means of the capacitor 27 and the variable resistor 23. Tuning after manufacture can be done in a simple manner by rotating the variable resistor 28. The vibrato effect is induced by introducing a frequency modulated signal through the input terminal 33, thereby varying the voltage of the base 23 of the transistor 21. Since measures are taken for temperature compensation and stabilization against variations of the direct-current voltage, variations of frequency with temperature and fluctuations with variations of power source voltage are extremely small. Accordingly, once tuning has been carried out, there is almost no necessity for retuning.

The excitation of the initial stage of the parametrically excited frequency divider is accomplished by installing a tertiary winding in the aforesaid inductor 25 of FIG. 3 and causing the required amount of direct-current bias current to flow through the said winding as a superimposed current. An embodiment of a circuit suitable for this purpose is illustrated in FIG. 4, wherein the parametrically excited frequency divider is composed of the above-mentioned tertiary winding 38, a coupling capacitor 39, a windings 4th, and a capacitor 41. In addition, the circuit contains a direct-current bias power source 42, a choke resistor 43, and an output terminal 44.

The details of the frequency dividers will be more clearly apparent by reference to the following description.

In general, if a non-linear inductance L or a capacitance C contained in a resonance circuit is excited periodically to vary the said inductance L or said capacitance C, and if the resonance circuit is in tune approximately with a /2 subharmonic, an oscillation of /2 subharmonic will be generated therein. This is oscillation due to parametric excitation, and if this parametric excitation is utilized, it is possible to halve the excited frequency. This is an intrinsic characteristic of such a non-linear element, and if the said element is connected in cascade arrangement of n stages, it is possible to obtain /211 frequency divisions.

Frequency dividers which have been assembled on the basis of the above-stated principle are adapted to form one part of the system shown in FIG. 2. The excitation of the initial stage of these frequency dividers may be effected as indicated in FIG. 4-, and thereafter the necessary number of stages of this type of circuit may be connected in cascade arrangement. By way of example, an embodiment for the case of three stages is shown in FIG. 5. The first stage comprises a first stage windings 40a, a first stage capacitor 41a, and a first stage choke resistor 43a. Similarly, the second stage comprises windings 40b, a capacitor 41b, and a choke resistor 43b; and the third stage comprises windings 400, a capacitor 410, and a choke resistor 430. A direct-current bias power source 42 is connected between the primaries of said windings and the said choke resistors. The input is received through an input terminal 45, and the first, second, and third stages are provided, respectively, with output terminals 46a, 46b, and 460. If the input frequency has the value 7, then the output frequencies obtained from the said output terminals 46a, 46b, and 46c are, respectively, f/Z, f/4, and f/8.

Since such frequency dividers as described above are assembled from only iron cores or ferrite cores, capacitors, and resistors or choke coils and require only a lowvoltage power source, their construction is simple and of low cost. Moreover, if inductors and capacitors meeting the requirements of constant, specified values are selected, adjustment processes during manufacture will be unnecessary, and maintenance care after assembly will also be unnecessary. The utilization of such circuits in an electronic musical instrument removes the prime ditliculty attendant to the conventional electronic organs and solves a large portion of the troubles incurred heretofore relative to the electrical systems of electronic organs. In this respect, this feature of the present invention may be considered to be an epochal progress in the art.

The details of the envelope circuits will be best understood by reference to the following description.

The rise and attenuation conditions of the oscillation for the general case of parametron excitation are as described below.

Referring to FIG. 6, the circuit shown comprises an exciting power source 47 operating at a frequency of 2]"; a contact 48 for switching the excitation on and off; a direct-current bias power source 49; windings St); a capacitor 51 which, together with said windings 50, forms a parametron; an input terminal for a feeble signal current at a frequency of f; a coupling resistor 53 for the input; and a damping resistor 54.

Let it be assumed that in the circuit of FIG. 6 the contact 48 is initially open, and that an extremely low current I' at a frequency of f is flowing through the secondary side of the windings 50 as a so-called seed current. Then, if at a time Q, the contact 48 is closed to pass an exciting current, an oscillation of frequency f is caused to develop as an exponential function in the circuit consisting of the secondary side of the windings 50 and the capacitor 51. This development of the oscillation is represented graphically in FIG. 7a. If the current of frequency f is designated by i and time by l, the growth of said current i; with respect to time t may be mathematically expressed by:

i i Ekt where i the seed current Here, the larger the modulation index I of the inductance is, and the higher the quality factor of the tuning circuit formed by the inductor (the secondary of winding 50) and capacitor 51 is, the larger is the constant k. In other terms, the oscillation wave rise is rapid. Here I shall be expressed by the following equation. That is, when the inductance L of the tuning circuit consists of a constant inductance L and an which varies sinusoid-ally at a frequency 2 and its variation is designated by AL, 1 may be expressed by:

1=A.L/2L

When this oscillation current i increases above a certain magnitude, its amplitude is restricted by the non-linear characteristic of the core and settles down to a certain, definite value.

Next, the attenuation is effected in the following maner. When, at a certain time t the contact 48 of FIG. 6 is opened to stop the excitation, the oscillation, instead of stopping discontinuously, is attenuated again as an exponential function as indicated in FIG. 7b. The rapidity of this attenuation varies with magnitude of the damping resistance 54 of FIG. 6, the attenuation being longer if the value of the said resistance is higher.

By the use of these properties of parametrons, it is possible to effect the gating of a signal. During this operation, moreover, it is possible to vary the rise and attenuation characteristics of the signal. Furthermore, it is clear that, in contrast to a conventional electronic organ wherein the percussive noises emitted during gating of a signal present a problem, the instrument of the present invention which utilizes parametrons is absolutely free of this problem because of the principle of its signal gating.

FIG. 8 illustrates one embodiment of an envelope circuit suitable for use in the invention. A signal source 55 of frequency 21 supplies exciting current to a circuit which comprises a contact 63 for switching the exciting current on and off; a coupling resistor 56; a coupling transformer 57; windings 58; a capacitor 59, which, together with the said windings 58, forms the parametron-connection; resistors 60 and 61 for controlling the attenuation time; and a switching contact 62 for controlling the attenuation time. By opening and closing said switching contact 62, one of two values of the effective resistance of the resistors 60 and 61 may be selected. That is, if the resistances of resistors 60 and 61 connected in series are denoted by R and R the available effective resistances of the resistor pair are R +R and R Thus, it is possible to vary the attenuation time accordingly. The said contact 62 is preferably included in the contacts 6 shown in FIG. 2, being switched as necessary, during the playing of the musical instrument to control the damping time. The aforesaid switch contact 63 for the exciting current is actuated by a keyboard and relates to the switching on and off of signals. It is included in the keyboard mechanism 4 of FIG. 1.

As methods of starting and stopping oscillation, the following cases are conceivable: the case wherein the seed current is not supplied, and the exciting current is switched on and off; the case wherein the seed cur rent is kept supplied, and only the exciting current is switched on and off; and the case wherein both the exciting current and the .seed current are switched on and off. However, in the case wherein the seed current is kept supplied, and only the exciting current is switched on and off, the ratio of the output levels of the case of the seed current only and the case wherein excitation is effected, and oscillation is taking place with a constant amplitude may become a problem. Nevertheless, if the ratio of the output levels of the two cases is db or higher, it may be assumed that there will be no problem. At present, 80 db is a value which can be amply realized.

By assembling the various circuits as described in the foregoing disclosure, it is possible to construct an electronic musical instrument which achieves the initially stated objects and advantages of the invention.

FIG. 9 shows a detailed diagram of an embodiment of a sound source circuit system and an envelope circuit system for the case of six frequency divisions. This diagram corresponds approximately to that of FIG. 2. The reference numerals which are common to both FIGS. 2 and 9 designate the same or equivalent parts. Referring to FIG. 9, the sound source circuit comprises an oscillator 9 with an output frequency of 1; frequency dividers It), 11, 12, I3, and 14 with output frequencies of f/Z, f/ 4, f/S, f/ 16, and f/32, respectively; and a terminal VII for connecting the direct-current power source, which is commonly connected to the oscillator 9 and frequency dividers 1t], 11, 12, 13, and 14. A tone selection and tone color circuit 3 is connected between the sound source circuit and the envelope circuits comprising envelope circuits 15, 16, 17, 18, 19, and 20 with output frequencies of f/Z, f/4, f/8, f/16, f/32, and f/64, respectively, and output terminals I, II, III, IV, V and VI, respectively. Said circuit 20 functions doubly as also a frequency divider, The aforesaid tone selection and tone color circuit 3 is controlled by a keyboard mechanism 4 and a tone stop mechanism 5 and is provided with an output terminal I for an undivided frequency 1 from the oscillator 9, which transmits a wave form which is especially free from attenuation effect. The envelope circuits are connected to the envelope control contacts and contact actuating mechanism 6.

In FIG. 9, the tone selection and tone color circuit 3, the keyboard mechanism 4, and tone stop mechanism 5 are shown in simplified forms. In the case shown in FIG. 9, tones of six different frequencies, C C C C C and C can be selected, and their respective fundamental frequencies are f/64, f/32, f/16, 'f/ 8, f/4, and f/Z. In the tone stop mechanism 5 illustrated, the selection of only the 2nd and 4th harmonics is done. However, by taking signals from other systems, it is possible to obtain tone colors which are rich in variations. In the said mechanism 5, the tone stop Z relates to the fundamental frequency; tone stop Y relates to the second harmonic; and tone stop X relates to the fourth harmonic. The control manipulation members of the keyboard mechanism 4 and tone stop mechanism 5 are indicated by arrows, and at the time of manipulation, each said member actuates the contacts through which the broken line extending from its arrow passes. However, the tone stop mechanism 5 is constructed as a holding mechanism so that once it is set, it continues to function until it is reset. The contact control is so con structed that the contacts are not closed by only the action of the tone stop mechanism 5. That is, only when the keyboard mechanism 4 is actuated, only the contacts at the intersections of the broken extending from the arrow which corresponds to the part thus actuated close. For example, if the mechanisms of X and Z are set, and the key C is depressed, only the two contacts at the intersections of the broken line extending from the arrow C and the broken lines extending from the arrows X and Z will be closed. Consequently, signals of frequencies f/ 2 and f/ 8 will be obtained at the output terminals I and II.

By varying the combinations and number of contacts driven by the tone stop mechanism 5, an almost unlimited number of tone color variations are obtainable. Moreover, it is also possible to adapt the aforesaid mechanism so that the most frequently used combinations can be made beforehand.

ft is a unique feature of the present system that the contacts not only open and close the flow paths of signal currents, but also simultaneously drive the envelope circuits, In most cases, heretofore, wherein arrangements similar to that of the present invention were used, it has been necessary to make the number of envelope circuits the same as that of the contacts or, if the number of envelope circuits were to be made small, to use a complex contact mechanism; or, if such complications of apparatus were thought to be undesirable, the system was adapted to directly open and close the paths of only the signals, and the envelope circuits were used in only one portion. In the final case, the creation of percussive and transient noise at the time of signal opening and closing has been almost impossible to avoid, and at least some measures have been necessary for the prevention of this disadvantage. The system of the present invention has solved all such difficulties as complications of apparatus or decreased performance. Moreover, the system of the present invention has the unique advantage in that, in the case of the lowest octave, a single circuit functions doubly as a frequency divider and an envelope circuit.

While particular embodiments of the present invention have been described, it will, of course, be understood that the invention is not intended to be limited 8 thereto, since many modifications can be made in the above described details without departing from the nature and spirit of the invention, and it is contemplated by the appended claims to cover all such modifications as fall within the true spirit and scope of the invention.

What We claim is:

1. An electronic musical instrument which comprises, in combination,

a sound source circuit consisting of a wave producing stage having a plurality of master oscillators each of which is tuned to a different fundamental scalar frequency;

an assembly of one-half frequency divider stages each of which consists of a parametric device including a non-linear element, said frequency divider assembly stages being connected in a cascades arrangement, said master oscillators being connected at their output sides to the first of the frequency divider stages of said assembly to excite the frequency divider of said first stage;

tone rise and attenuation means for imparting rise and attenuation to the sound signals, said means consisting of a plurality of envelope circuits each of which consists of a second parametric device, said envelope circuits being respectively coupled to the output sides of said master oscillators and frequency divider stages;

switch means for carrying out the make and break-01f of the parametric exciting input power of said tone rise and attenuation means, thus causing the make and break-01f of the output tones; and,

a keyboard arrangement having keys to start the wave train of said wave producing stage and actuate said switch means.

2. An electronic musical instrument as claimed in claim 1, wherein each master oscillator is a transistor oscillator, the output side of said transistor oscillator being connected to input side of the corresponding parametric frequency divider to excite said divider.

References Cited by the Examiner UNITED STATES PATENTS 2,403,090 7/1946 Lansen 84-119 2,721,264 10/1955 Selz et a1. 321-68 2,825,813 3/1958 Sperling 33l176 X 2,924,784 2/1960 Peterson 84-124 2,930,003 3/1960 Wilson 33l76 2,948,818 8/1960 Goto 33l165 X 2,948,819 8/1960 Goto 331- X ARTHUR GAUSS, Primary Examiner.

CARL W. ROBINSON, GEORGE N. WESTBY,

Examiners. 

1. AN ELECTRONIC MUSICAL INSTRUMENT WHICH COMPRISES, IN COMBINATION, A SOUND SOURCE CIRCUIT CONSISTING OF A WAVE PRODUCING STAGE HAVING A PLURALITY OF MASTER OSCILLATORS EACH OF WHICH IS TUNED TO A DIFFERENT FUNDAMENTAL SCALAR FREQUENCY; AN ASSEMBLY OF ONE-HALF FREQUENCY DIVIDER STAGES EACH OF WHICH CONSISTS OF A PARAMETRIC DEVICE INCLUDING A NON-LINEAR ELEMENT, SAID FREQUENCY DIVIDER ASSEMBLY STAGES BEING CONNECTED IN A CASCADES ARRANGEMENT, SAID MASTER OSCILLATORS BEING CONNECTED AT THEIR OUTPUT SIDES TO THE FIRST OF THE FREQUENCY DIVIDER STAGES OF SAID ASSEMBLY TO EXCITE THE FREQUENCY DIVIDER OF SAID FIRST STAGE; TONE RISE AND ATTENUATION MEANS FOR IMPARTING RISE 